A capsule for a powder has a body which is provided with an internal chamber (21) to hold the powder and first and second openings to an exterior environment. The body is adapted to be displaced from a filling state, in which the first and second openings are placed in fluid communication with one another through the internal chamber thereby enabling an airflow to be created through the body from the second opening to the first opening which is able to entrain powder in the exterior environment into the internal chamber for filling thereof, to a sealing state in which the internal chamber is sealed from the exterior environment so as to retain the powder held therein.